is that possible?

[volaff]

I would have the need to create a single part from a set, that is, as if it were all a single piece (part).

Is it possible to do that?

I saw that saving from the file together a part file creates a body with surfaces. .
Is that normal?

 

[MassiVonWeizen]

as always and as you were told, laughed and repeated several times:
to understand whether what happens is normal or not you have to have the file.
As a rule, if there are parts that have only bodies should not create surfaces, but this is impossible to know for certain.

even if you manage to create a part with only bodies then it is not said that with the only pair you manage to generate a single body because the geometry could not allow it (tangencies, light between the bodies between the most obvious cases) and therefore you have to work on compensatory extrusions

 

[volaff]

as always and as you were told, laughed and repeated several times:
to understand whether what happens is normal or not you have to have the file.
As a rule, if there are parts that have only bodies should not create surfaces, but this is impossible to know for certain.

even if you manage to create a part with only bodies then it is not said that with the only pair you manage to generate a single body because the geometry could not allow it (tangencies, light between the bodies between the most obvious cases) and therefore you have to work on compensatory extrusions

Thank you for the complete answer.
I tried to make a mirror with solid union and it seems to have worked even if the first time it made crab.

Thank you very much.

Of course if, for example, in a file part I use the "surface filling" fuination I will always have a solid + 1 surface body.

Good evening!